Double-roller lever-escapement



H. COLOMB. DOUBLE ROLLER LEVER ESCAPEMENT.

APPLICATION FILED JAN. 5, 1920.

Patented June 29, 1920..

Invelv 1' HColomb,

fi/(VW A ttorzzeu PATENT". OFFICE.

HENRI. comma, or TAVANNES, SWITZERLAND.

DOUBLE-ROLLER EvER-ns'oAPEivrENT.

Application filed January 5, i920. *seriaim. 345,643.

To all whom it may concern Be it known that I; HENnrCoLoMB, citizen of the Swiss Republic,,residing at Tavannes, in the Canton or Berne, Switzerland, have invented certain new and useful Improvements in Double-Roller Lever-Escapements, of which the following is a specification.

In double roller lever escapements hitherto manufactured, the overswinging organs are constituted by the small roller and the prong. The whole is completed by the horns of the fork, which start operating, with the roller pin, when the relative position of the prong and of the notch in the small roller do not afford, momentarily, any safety to the overswinging motion. As a matter of fact,'the horns of the fork are appendices giving the watchmaker a certain amount of work and trouble on securing proper endshake of said horns.

Considering the ratios heretofore adopted by watch-manufacturers in the construction of double-roller lever escapements, those horns are absolutely necessary. It is generally admitted as a fact that the diameter of the circumference described by the outermost point of the roller pin from the pivoting center of the roller, on the one hand,

and the diameterof the small roller. on the other hand, should be in a ratio very close to Figure 1, in the annexed drawings, shows that the aforesaid ratio and in normal conditions of construction and running, viz: for an angle of lever pallet of 12 and for a like angle of balance pallet of 40, it is not possible, even though the diameter of the notch be reduced to a strict minimum, taking into account end-shake of pivots and de fects in the manufacture, to do away with the fork-horns. The hatched portions of the aforesaid figure plainly show that safe overswinging motion would-no longer exist, should the horn side be finished off at right angles.

Fig. 1 is a plan detail of the usual type of escapement having horned forks, and

Fig. 2 is a top plan view of the improved 1 form of the escapement.

Referring to the aforesaid Fig. 2 in which is represented, so far as required for understanding the invention, a double roller lever escapement in which-the angle of the lever pallet is equal to that of the ordinary escapemen't shown in Fig. 1, the fork a is shown in its position as occupied when it butts against the side 6 and when the roller pin 0 is about to part from the fork. The position of the notch d of the small roller is shown by a dotted line in the position as occupied in relation to the prong at the very moment when safe overswinging motion is again secured by said prong. The figure shows that the relative position of the roller-pin, of the left inward side of the fork is such that said organs themselves prevent any overswinging motion. Horns, therefore, would be of no use and have been done away with, while perfected overswinging remains unaffected.

Should we examine the conditions, due allowance being made, in which the horns may be done away with, all proportions and ratios of the horns remain unchanged, as

the dimensions of the escape wheel and the shape of the teeth thereof, we shall notice that it has been sufiicient to alter, comparatively to escapements ordinarily used, the distance 0 P from the farthermost point of the roller pin to the pivoting'center of'the roller, at the pivoting center itself, or to lengthen the ray of the small roller, or both altogether. In other words, it will be sufficient to change the proportion existing, on the one hand, between the diameter of the circumference described by the farthermost point of the pin from the pivoting center of the member bearing said pin, and the diameter of the small roller, on the other hand. In the example shown, said proportion is about whereas it is in Fig. 1. This alteration, though not affecting end-shake of roller and back lash of prong with said notch, permits of reducing the diameter of Specification of Letters Patent. Patented, June 29, 19211 saidproportions and ratios would influence said notch, the result being that the spring may be kept in use much longer. In the examples shown, in which the angles of the lever pallets are 12 everywhere, one has, for the escapement represented Fig. 1, a balance pallet angle of 40, whereas, in Fig. 2, said fact, locking rest is a defect inherent to the latter styles of watches, and a purpose of the hereinbefore mentioned enlargement of the balance pallets angle is to do away with said defect.

I claim as my invention:

1. An escapement comprising a lever having hornless forks, a prong on the lever, a balance wheel including concentrically ar ranged large and small rollers the smaller of which is provided with a notch, and a roller pin mounted on the large roller so that the proportion existing on the one hand between the diameter of the circumference described by the farthermost point of the roller pin from the pivot center of the large roller and the diameter of the small roller on the other 15 hand is reduced so that safe overswinging motion is secured in all positions of the balance wheel.

2. An arrangement as claimed in claim 1 wherein the proportion existing on the one 20 hand between the diameter of the circumference described by the farthermost point of the roller pin from the pivot center of the roller bearin such pin and the diameter of the small rolfer is inferior to In testimony whereof I affix my signature.

HENRI COLOMB. 

